The disclosed technology relates to an electronic ink microcapsule and a method for producing the same.
With the advances in information science and technology, the flat panel displays are developed to possess the features of lightness, low power, and low drive voltage are becoming desirable. The development of electrophoretic display technology, in particular, microcapsule electrophoretic display technology has become rapid.
Microcapsule electrophoretic display technology is a reflective display technology based on electrophoresis of charged particles suspended in a dispersion medium, and this technology has the following characteristics: i) microcapsules mixed in the adhesive liquid can be applied on the backplate by inkjet printing, coating, etc. so that it is suitable for flexible displays; and ii) microcapsule electrophoretic display technology employs electrophoretic particles and insulation suspension liquid encapsulated in microcapsules, which can inhibit the aggregation and deposition of electrophoretic particles, thereby enhancing the stability and life of the electrophoretic display. Due to the above characteristics of the microcapsule electrophoretic display technology, it has been widely studied.
Nakamura investigated microcapsules in a gelatin-arabic gum system, in which the capsule wall of the microcapsules is attached on the droplet core after precipitation resulting from agglomeration of gelatin as a polycation and arabic gum as a polyanion in the aqueous phase. However, arabic gum tends to degrade during the usage of such microcapsules, and long-term use ruins the capsule barrier. Moreover, arabic gum is expensive so that such a system is not suitable for a large-scale commercial use.
Therefore, researchers have developed microcapsules containing silicone, which employs gelatin as a polycation, sodium carboxymethyl cellulose as a polyanion, and anionic perfluorinated surfactant as an emulsifier. During preparing a display from the microcapsules produced according to this process, the perfluorinated surfactant, as a small molecule material, tends to reduce the surface tension of the used adhesive, so that the adhesive coated on the backplate shrinks and can not wet the backplate, resulting in an increase in the product defect rate.
In addition, researchers also developed fluorine-containing microcapsules, which are based on gelatin as a polycation, and a copolymer of vinyl silicone oil, styrene and maleic anhydride as a polyanion. Such microcapsules have the following disadvantages during use. Firstly, carboxyl (—COOH) remaining in the gelatin may easily lead to deterioration of the electrophoresis solution or the electrophoretic particles, and the stability and barrier of the capsule wall is poor; secondly, the dye in the electrophoresis solution is instable in chemical properties and tends to fade; and thirdly, the terminal double bond in silicone oil is an active group and tends to cause deterioration of dyes.